Non-Circular TSV Landing Pads for Dense 3D IC Routing
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Solution Overview
Problem
Through-silicon-vias (TSVs) in integrated circuits face issues such as open circuits due to etching inaccuracies, undercuts, and shorts, as well as non-uniformity in bump heights and epoxy voids, which affect the yield and routing density of 3D IC stacks.
Innovation Solution
The use of non-circle shaped landing pads and additional dummy TSVs to increase TSV density, allowing for uniform etching and improved routing flexibility, reducing the probability of epoxy voids and enhancing power delivery capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If traditional circular landing pads are used, then the structure is simple and easy to manufacture, but routing density is limited and power delivery capabilities are constrained
Solution Approach 1:
The patent applies asymmetry by changing the landing pad shape from traditional circular to non-circular geometries (such as rectangular or custom-shaped pads). This asymmetric design allows for increased routing density and improved power delivery capabilities while maintaining manufacturability through standard photolithography processes.
Solution Approach 2:
The patent utilizes dimensionality change by extending the landing pad shape from a simple circular form to multi-dimensional non-circular configurations. This allows interconnects to approach the landing pad from multiple directions, increasing routing flexibility and density without proportionally increasing the footprint area.
2Manufacturing precision
If TSV etching is performed with standard parameters, then the process is simple and fast, but etching inaccuracies cause open circuits and undercuts
Solution Approach 1:
The patent applies preliminary action by performing dummy TSV etching steps before the actual TSV formation. These preliminary dummy TSVs are etched to establish uniform etching conditions and parameters across the substrate, ensuring that subsequent production TSVs achieve accurate dimensions and proper landing pad contact without requiring complex real-time adjustments.
Solution Approach 2:
The patent utilizes parameter changes by modifying etching conditions (such as etch rate, plasma power, pressure, or chemistry) based on the presence and removal of dummy TSVs. The etching parameters are adjusted to account for the initial dummy TSV structures, allowing for precise control of TSV depth and diameter to prevent undercuts and open circuits.
3Quantity of substance
If substrate bump pitch is reduced to increase I/O density, then more I/O connections are achieved, but non-uniformity in bump heights increases causing epoxy voids
Solution Approach 1:
The patent applies local quality by implementing non-uniform landing pad designs where the size, shape, and position of landing pads are locally optimized based on their specific location and function. This allows for compensation of bump height variations in different regions of the substrate, ensuring proper epoxy filling and eliminating voids while maintaining high I/O density through reduced pitch.
Data Source
AI summary
An apparatus is provided which comprises: a plurality of interconnects to couple a silicon interposer to a substrate; and a landing pad configured in a non-circle shape, wherein the plurality of interconnects are adjacent to the landing pad at one end of the plurality of interconnects through a plurality of vias.